A major goal of this project is the analysis of the reinforcing effects of opiates and the development of methods for extinguishing the reinforcing effects, both primary and conditioned, which are the underlying behavioral phenomena of drug dependence. Further efforts to distinguish non-specific and specific influences of agents which alter the self-administration behavior of animals toward opiates will be conducted. The relationship of opiate-based reinforcement to dopaminergic and/or noradrenergic brain mechanisms and to the reinforcement associated with d-amphetamine will be explored further. Methadone will be the subject of self-administration studies in direct comparison to morphine in rats. Studies on the effects of prenatal exposure to methadone on behavioral development of the offspring will be continued.